Microsoft 365 Alert – Service Degradation – Exchange Online – Some users are receiving a misleading error when replying to or forwarding email through Outlook on the web – RESOLVED

25/03/2025 08:55:00 AM

NHSmail Reference: INC46485375

Microsoft Reference: EX1037867

Issue Status: RESOLVED

Issue Description: Users are receiving a misleading error when replying to or forwarding email through Outlook on the web.

More info: The error is misleading and doesn’t prevent users from replying to or forwarding email through Outlook on the web.

Final Update: 27/03/2025 08:40:00 AM – Microsoft have confirmed with affected users that their fix deployment has resolved the issue. Previously affected users may need to restart Outlook on the web to ensure that their fix has been implemented.

Scope of impact: Impact is specific to some users, who are served through the affected infrastructure, attempting to reply to or forward email messages through Outlook on the web.

Root cause: A code change that intended to improve service performance has introduced an impacting code regression.

Next steps: Microsoft are continuing to evaluate and analyze the affected code change to better understand why impact wasn’t caught during the update testing and validation phase. This is to ensure similar impact doesn’t occur in future and to continue their ongoing efforts to improve the resiliency of their service for all users.